Cylindrical grinding machine



Nqv. 9, 1948. H. A. SILVEN CYLINDRICAL GRINDING MACHINE 4 Sheets-Sheet 1 Filed June 11, 1945 I -HERBERT A. SIM/EN n u u u Nov. 9, 1948.

CYLINDRICAL GRINDING MACHINE Filed June 11, 1945 4 SheetsSheet 2 HERBERT A. S/LVEN H. A. SILVEN 7 2,453,678

Nov. 9, 1948. H. A. SlLVEN 2,453,678

, v CYLINDRICAL GRINDING MACHINE Filed June 11, 1945 4 Sheets-Sheet 3 HERBERT A. 5/ LVEN Nov. 9, 1948. H. A. SILVENI 2,453,678 7 CYLINDRICAL GRINDING MACHINE Filed June 11, 1945-, 4 Sheets-Sheet 4 x v 30 \IO I I A 333 a b Patented Nov. 9, 1948 CYLINDRICAL GRINDING MACHINE Herbert A. Silven, Worcester, Mass, assignor to Norton Company, Worcester, Mass, a corporation of Massachusetts Application .lune 11. 1945, Serial No. 598,799

11 Claims.

This invention relates to grinding machines, and more particularly to a hydraulically operated cylindrical grinding machine.

One object of the invention is to provide a simple and thoroughly practical grinding machine. Another object of the in vention is to provide a hydraulically operated cylindrical grinding machine which is arranged so that either a hand or an automatic cycle of operation may be readily obtained. Another object of the invention is to provide a hydraulically operated cylindrical grinding machine in which a traverse grinding operation may be obtained, in which the grinding wheel is automatically fed into the work at the 'ends of the reciprocatory stroke of the work piece. Another object of the invention is to provide a grinding machine in which the hydraulically operated table reciproeating mechanism and the hydraulically operated grinding wheel feeding mechanism may be independently and manually controlled or in which the infeeding movement of the grinding wheel may be automatically actuated at the ends of the work table stroke.

Another object of the invention is to provide 5 a hydraulically operated cylindrical grinding machine in which a selector valve is provided by means of which the machine may be readily set up for either a traverse grinding operation with an automatic infeed at the ends of the work table stroke or the machine may be set up for an automatic cycle of operation in which a plunge-cut feeding movement of the grinding wheel is obtained and automatic rapid return.

Another object of the invention is to, provide a feeding mechanism in which a vane-type motor is provided. to rotate the feed screw either continuously for a plunge-cut grinding operation or intermittently at the ends of the table stroke or a traverse grinding operation. Another object of the invention is to provide a control mechanism for said vane-type motor which is arranged to allow the motor vane to rotate at a comparatively rapid rate during its initial movement on either a plunge-cut or a traverse grinding operation to take up the backlash in the feeding mechanism parts before the grinding wheel moves into grinding engagement with the work piece. A further object of the invention is to provide a, shuttle type valve, the speed of movement of which may be regulated so as to meter a predetermined amount of fluid from the vane feeding motor to obtain an initial rapid movement of the motor vane so as to take up theback lash between the feed screw and nut before the cylindrical grinding operation is started. Other parts will be in part obvious or in part pointed out hereinafter. I

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts, as will be exemplilied in the structure to be hereinafter described, and the scope of the application of which will be indicated in the following claims.

One embodiment of' the invention has been illustrated in the drawings, in which:

Fig. 1 is.a front elevation of the improved hydraulically operated cylindrical grinding machine;

Fig. 2 is a diagrammatic illustration of the hydraulic control mechanisms and a simplified electricdiagram of the work driving mechanism;

Fig. 3 is a'fragmentary front elevation, on an enlarged scale, of the wheel feeding mechanism as shown in Fig. 1, having the manually operable feed wheel removed;

Fig. 4 is a fragmentary sectional view, taken approximately on the line 4-4 of Fig. 3; Fig. 5 is a vertical sectional view, on an enlarged scale, taken approximately on the line 5-5 of Fig. 3, through the hydraulically actuated continuous infeeding mechanism;

Fig. 6 is a fragmentary sectional view, on an enlarged scale, through the latch stud for holding the power feed mechanism in an operative position for an automatic infeeding movement of the grinding wheel;

Fig. 7 is a similar fragmentary sectional view, on an enlarged scale, showing the latch pin in a position for a hand feeding operation;

Fig.-8 is a fragmentary sectional view, on an enlarged scale, taken approximately on the line 8-3 of Fig. 4, showing the stud. locating device;

Fig. 9 is a vertical sectional view, on an enlarged scale, through. the selector valve; and

Fig. 10 is a fragmentary view, taken approximately on the line Ill-48 of Fig. 9, showing the stop device for limiting the rotary movement of the selector valve.

An improved hydraulically operated cylindrical grinding machine has been illustrated in the drawingsfcomprising a, base l5 which serves to support a longitudinally reciprocable work supporting. table II. The table I is arranged to be traversed. or reciprocated longitudinally on a fiat way l2 andv a V-Way l3 formed on the upper surface of the base ill. The table II may be traversed longitudinally by a, manually operable hand Wheel. 14 througha manually operable traverse mechanism. to be hereinafter described.

Table reciprocation A fluid pressure mechanism is provided for reciprocating the table II longitudinally comprising a cylinder l5 which is fixed relative to the base in. The cylinder l5 contains a slidably mounted piston l6 which is fixedly connected to a double end piston rod H. The opposite ends of the piston rod ll are connected by depending brackets I8 and i9 fixedly mounted on the under side of the table 5 l at its opposite ends.

A table reversing or control valve is provided for controlling the admission to and exhaust of fluid from the cylinder I5. When fluid under pressure is passed through a pipe 2| and a passage 22 into a cylinder chamber 23, it will cause the piston l6 and table II to move toward the right (Fig. 1). During the movement of the piston it toward the right, fluid within a cylinder chamber 2 will exhaust through a passage 25 and through a pipe 26 to the control valve 20.

The table I l serves as a support fora rotatable work piece 2?. The work piece 21 is supported on a headstock center 28 and a rootstock center 29 which are in turn supported by a headstock 30 and a footstock 3|, respectively. The headstock 30 is preferably a motor driven headstock comprising an electric motor 32 which is provided with a driving pulley 33 (Fig. 2) which is connected by multiple V-belts 34 with a pulley 35:1;0 drive the work piece 21 during a grinding operation.

Grinding wheel feed A transversely movable wheel slide 38 is arranged to move transversely relative to the base It on a V-way 39 and a flat way M! (Fig. 1). The wheel slide 38 is provided with a rotatable wheel spindle which supports a rotatable grinding wheel 42 at its left-hand end (Fig. 1). The spindle and grinding wheel 42 are preferably positively driven by a suitable driving mechanism such as, for example, an electric motor 43 which is mounted on the upper surface of the wheel slide 38. The motor M5 is provided with an armature shaft 44 which supports a multiple V-groove pulley 45. The ulley 45 is connected by multiple V-belts 46 with a multi-V-grove pulley 41 which is mounted on the right-hand end of the wheel spindle.

A nut and screw feed mechanism is provided for feeding the wheel slide 38 transversely relative to the base ll). This mechanism may comprise a rotatable feed screw 50 which meshes with a depending h-alf nut 5! fastened to the under side of the wheel slide 38. A reduced end portion 52 of tthe feed screw 5!] is slidably keyed within a rotatable sleeve 53. The sleeve 53 is journalled in anti-friction bearings 54 and 55 which are in turn fixed relative to the base H3. The right-hand end of the feed screw 50 is journalled in a suitable bearing (not shown) in a slidably mounted sleeve 56 which is slidably keyed within a portion of the base H].

In order to move the wheel slide 38 rapidly to and from a grinding position, a hydraulically operated mechanism is provided comprising a hydraulic cylinder 51 which contains a slidably mounted piston 58. The piston 58 is connected to a double end piston rod 59, the left-hand end of which is fastened to the slidably mounted sleeve 56. arranged in axial alignment with the axis of the feed screw 50.

A control valve 6% is provided for controlling the admission to and exhaust of fluid from the cylinder 51. When fluid under pressure is admitted.

As illustrated in Fig. 2, the piston rod 59 is through a pipe 6| into a cylinder chamber 62, it will cause the piston 58, the feed screw 60, and the wheel slide 38 to move to an operative position relative to the work piece 2? to be ground. During this movement, fluid within a cylinder chamber 63 exhausts through a pipe 64. Similarly, when fluid under pressure is admitted to the cylinder chamber 63, the piston 58, the wheel slide 38 and the grinding wheel 42 will be moved to a rearward or inoperative position.

A manually operable feed wheel i8 is provided for manually rotating the feed screw 5!] to impart a transverse feeding movement to the wheel slide 38. The feed wheel 10 is rotatably supported on a rotatable shaft 72 which is journalled in beari gs (not shown) in the base I0. The feed wheel 10 is provided with the old and well known micrometer adjusting mechanism 15 having a feed gear 13 fixedly mounted on the shaft 12, which is substantially the same as that shown in the expired U. S. Patent No. 762,838 .to C. H. Norton dated June 14, 1904, to which reference may be had for details of disclosure not contained herein. A pinion 16 (Fig. l.) is formed integral with the shaft '12 and is mounted to rotate with the hand wheel 10. The pinion l6 meshes with a gear ll mounted on a rotatable shaft E8. The gear 11 meshes with a gear '59 which is formed integral with the sleeve 53. It will be readily apparent from the foregoin disclosure that a rotary motion of the hand wheel ill will be transmitted through the gear mechanism above described to rotate the feed screw 50 so as to cause a transverse feeding movement of the wheel slide 38.

A power operated feeding mechanism is provided which is arranged to rotate the feed screw 50 either intermittently at the ends of the table stroke for a traverse grinding operation or continuously for a plunge-cut grinding operation. Thi mechanism preferably comprises a rotary vane type motor having a rotatable rotor shaft 86. A rotor 8'? is formed integral with the shaft 86 and serves as a support for a single vane 88 (Fig. 2). A fixed plate 89 within'the motor 85 serves to limit the rotary motion of the vane 88. When fluid is admitted through a passage 9!] into a motor chamber 9|, the rotor Bl and vane 88 will be moved in a counterclockwise direction (Fig. 2) to cause an infeeding movement of the grinding wheel 42. During this movement, fluid within a 'motor chamber 92 will exhaust through a passage 93.

A control valve 95 is provided for controlling the admission to and exhaust of fluid from the motor 85. The valve 95 comprises a valve stem 95 having plurality of valve pistons formed integrally therewith so as to provide a plurality of valve chambers 91, 98, 99, ill!) and I0]. In the position of the parts illustrated in Fig. 2, fluid under pressure enters the valve chamber 99 and the passage and passes into the motor chamber 9| to start a counterclockwise rotation of the vane 88 to produce an infeeding movement of the grinding wheel 42. The valve is preferably hydraulically actuated in timed relation with the other mechanisms of the machine. A pipe I03 is connected with the valve chamber llli and serves to convey fluid under pressure to move the valve stem 96 to its extreme left-hand end position (Fig. 2). Similarly, a pipe 504 is connected at the other end of the valve 95 to admit fluid to or exhaust fluid from the valve chamber 91 formed at the lefthand end of the valve 95. When fluid under pressure is passed through the pipe Hi3 into the chambi l Ml, the valve stem 96 will be moved toward .the left (Fig; 2:). toreverse the directionbfvmove- The casing M141. isprefer-ably fixedly mounted to a flange H5 (Fig. 5) which is formed integral with a rotatable sleeve H6. The. sleeve .IItiiis journalledin an aperture 'I-I Iwhich is .formedintegral with'lthevane -motor-85. The casing I I4 is arranged: so thatthe gear I I3 maybe movedin a clockwise directioninto either the position I I3a or II3b so that a stop abutment H8 which is integral with the casing H4; may be'swung into an operative positionint hepathof a stop abutment I I9 carried. by the manually operable feed wheel I0. The stop abutment II9 serves as a positive stop to limit the rotary infeeding movement of the hand wheel I0.-

Thecasing H4 which supports the feed gearing above described may be moved to an operative position, in which. position a slidably mounted latch stud. I having a reduced irregularly shaped'portion or pin I221 mayslide intoengagement with. a locating surface I22 on a block I23 fixed relative to the base I 0 of the machine. When the pineI 2I is in. the position IZia (Fig. 6), it serves to locate the casing I I4 and the gear H3 in position H311. when it is desired tomove the gear Il -3 from position II'3a into position H131), the latch stud I20 may be rotated counter-- clockwise to position the pin I2 in position I-2Ib as shown in Fig. 7. It will be readily apparent from the foregoing disclosure that, depending upon. the position of the pin I2 I, the gear I I 3 may be located either in position II3a or M3?) (Fig. 3).

In. order to. facilitate readily positioning and holding the latch stud I with the pin I2I either in position I2|a or IZIb, a pair of diametrically opposed elongated -shaped notches I24 are provided onsthe latch stud I20 (Figs. 4 and 8-). A spring-pressed ball H5 is supported by the frame H4 and is arranged to frictionally engage either one or the other of notches 'I24-on the latch stud I20. A. handle knob I25 is provided on the stud I20 to,facilitatepositioning of the pin. I21 (Figs. 3and- 5) so that the casing I'Iltmay be rocked to position the. driving gear H3 either .in. position Iii-3b for a hand feeding" operation, or in position Il 3a for a power feeding of me grinding wheel 42. It will be readily apparent fromthe foregoing disclosure, .thata rotary motion of the vane 38 of the motor '85 will be transmitted through the gear mechanism above described to rotatethe shaft 72 and the feed screw .50 and thus impart aninfeeding movementito the grinding wheel 42.

In order tofacilitate movement of the feed gear into. an operative position. a manually operable lever- I2tis pivotally mounted ona pin I28 (Figs. 3, eand 5) which is carried by-the housing I. The lower end of the lever 127 .is provided with an'aperture I29 which surrounds the outwardly extending" grooved portion. of the latchstud I20. The'lever i271 may be swung in a clockwise direction (Figs. 1 and 3) to throw the gear M13 intoan operative position. When. it is desiredto disconnect the power feed gear llz3from an operative position, the lever I2! may be swung in :a counw terclockwise direction (Fig. 4) to; withdraw the stud. I20 and the pin I2 I., that:is,.to=move it towardvthe right (Fig. 4)-towithdrawthe pin I2.I out of engagement with the locating surface I22; and the released tension of a spring I30:will shift the housing 444: to an. inoperativeposition with the gear I13 in the full line position as indicated in Fig. 3. The sprin I30: is connected between a stud. I'3I which is fixed relative to the base I05 and. a. stud 1.3.2. which is fixed relative to the gear casing I I4 (Figs. 3 and 4).. 3i and 4). which is fixedrelative tothe base, I0 limits the movement. ofrthe housing 114. towards an; inoperative position. The spring I 301- serves normally. to maintain the housing 1 I4 in engagement with the pin I33.

Wheel feed-control valve The feed controlvalve 60 is'preferably a piston type valve comprising a valve stem I having formed integrally therewith valve pistons I36, I31 and I30. An actuating knob I 39 is fixedly mounted'-on the outer end of the valve stem I35. The valve stem I35 is arranged so that, if desired, it may be locked in either a right-hand or a left.- handend-position (Fig. 2)- by means of a pin I40; A pair of transverse grooves I4! and I42 are provided in the valve stem I35. The slots MI and I42 are connected by a longitudinally extending slot..|.43. When the slot I43 is aligned with the pin I40, the valve stem I35 may bemoved longitudinally as desired. If it is-desired to latch the valve stem I35 in either a right-hand or a left-hand end position (Fig. 2), the valve stem I35 is moved into the desired position, after which the knob I39may be rotated so that the pin I 40 engages either the transverse groove I4I or the transverse groove I42 to lock the valve stem I35 against endwise movement so that the wheel slide 38 will be maintained either in a forward operative position or in a rearward inoperative position.

In the position of the valve 60 (Fig. 2 fluid under pressure passing through a pipe I44 enters a valve chamber I45 located between the valve pistons BB- and I3! and passes out through the pipe 64 intothe-cylinder chamber Gite movethe piston 58 and the wheel slide 38 to a rearward or inoperative position. During this movement of the piston 53, fluid within the cylinder chamber 62exhauststhrough the pipe SI into a valve chamber I 46- located between the valve pistons I31 and I38 and passes out through a pipe I41 into a reservoir I48.

Manual table traverse A manually operable traversing mechanism is provided for adjusting the table II longitudinally relative to the base Iii. This mechanism is actuated by the manually operable traverse wheel 54 which is rotatably mounted on a. stud-I50 A gear I51 is fixedly mounted torotatje with-the hand wheel I4. The gear I'5I meshes with a gear I52 which is keyed to a shaft 1153. The shaft I53 also. supports a gear I54 which meshes with a gear I55. The gear I55 is irotatably supported on a stud 656 and meshes with a rack bar I51 depending, from the under side of the work table II. It will be readily apparent from-the foregoing disclosure thata rotary motion of the hand wheel I'4 will be transmittedthrough ,thegearing above described to traverse the table H longitudinally. The direction of movement of the table I I will be determined bythe direction of rotation of the hand wheel I 4.

It is desirable to render the hand wheel I4 ing the hydraulic traverse or reciprocation of the table II. The gear I54 is preferably rotatably supported on the shaft I53 and is provided on its right-hand side face (Fig. 2) with clutch teeth I58 which are arranged to be engaged by clutch teeth formed on a slidably mounted clutch member I59. The clutch member I59 is slidably keyed to the shaft I53. In order to disconnect the clutch parts I58-I59, a fluid pressure cylinder I68 is provided which contains a slidably mounted piston I6I. The piston I6I is fixedly mounted on the right-hand end of the clutch member I59 (Fig. 2). In the position of the mechanism illustrated in Fig. 2, the clutch parts I58I 59 are maintained in engagement by means of a plurality of symmetrically arranged compression springs I62, only one of which has been illustrated in Fig. 2. When it is desired to disconnect the hand wheel I4 during hydraulic traverse of the table I I, fluid under pressure is passed through a pipe I63 into the cylinder chamber I64 to move the piston I6I toward the right (Fig. 2) so as to disconnect the clutch parts I58-I 59, thereby rendering the manually operable hand wheel I4 in-- operative.

Automatic control-headstock motor It is desirable to provide a suitable control mechanism for automatically starting and stopping the headstock driving motor 32 in timed relation with the other mechanism of the machine when an automatic cycle is employed. Power is supplied to the motor 32 from power lines I65. A manually operable switch I66 serves to close the motor circuit to facilitate manual control of the headstock when desired. It is preferable to provide a motor 32 which is of a variable speed type so that the speed of rotation of the work piece 21 may be readily adjusted. As shown diagrammatically in Fig. 2, an adjustable rheostat I61 is provided for regulating the speed of the motor 32. In actual construction, however, an

electronic control mechanism is preferably provided such as, for example, that manufactured by General Electric Company and known as the Thymotrol. A normally open limit switch I68 is provided in the motor circuit to facilitate automatically starting the motor 32 in timed relation with the other mechanisms of the machine during an automatic cycle. A hydraulically operated mechanism is provided for actuating the limit switch I68 comprising a hydraulic cylinder I69 which contains a slidably mounted piston I16. A piston rod I1! is connected at one end with the piston I16 and at the other end engages a roller [12 mounted on an actuating arm I13 of the limit switch I68. A compression spring I14 normally maintains the piston I19 in an uppermost position (Fig. 2) so that the switch I68 is normally open.

When fluid under pressure is passed through a pipe I15 into a cylinder chamber I16 above the piston I18, the piston I19 moves downwardly against the compression of the spring I 1-4 to close the normally open limit switch I58 and thus automatically start the rotation of the headstock motor 32. Similarly, when fluid is permitted to exhaust through the pipe I15, the released compression of the spring I14 will return the piston I10 to its uppermost position to open the limit switch -I68 and thereby stop the motor 32.

Table Reverse Valve The table reversing valve 20 is preferably a piston type valve comprising a shuttle type reversing valve member I86 which is provided with a plurality of integrally formed pistons I8I, I82, and I83. The reversing valve member I is preferably slidably mounted on a valve stem I84. A pair of independent valve members I and I86 are fixedly mounted on opposite ends of the valve stem I84 (Fig. 2). A spool-shaped member I81 is fixedly mounted on the right-hand end of the valve stem I84 and is provided with an annular groove I88 which is engaged by a stud I89. The stud I89 is fixedl mounted on a rock' arm I90. The rock arm I98 is fixedly mounted on a rock shaft I9I the outer end of which carries a table actuated reversing lever I92. A stud I93 is mounted adjacent to the upper end of the reversing lever I92 and is arranged in the path of movement of a pair of adjustably mounted table dogs I94 and I95. The table dogs I94 and I95 are adjustably supported by means of a longitudinally extending T-shaped slot I96 formed in the front edge of the work supporting table II.

A motor driven fluid pump 290 is provided for supplying fluid under pressure to the hydraulic system. The pump 208 draws fluid through a pipe 2IlI from the reservoir I49 and passes fluid under pressure through a pipe 202 to the various mechanisms of the machine. A relief valve 293 is connected in the pipe line 292 to facilitate maintaining the desired operating pressure within the hydraulic system. If pressure builds up beyond the predetermined pressure required, the relief valve 263 opens and by-passes excess fluid under pressure directly to the reservoir I 48.

The pipe 282 is connected to supply fluid under pressure to the table reversing valve 26. In the position of the valve 28 (Fig. 2), fluid under pressure from the pipe 282 enters a valve chamber 284 located between the valve pistons IBI and I82 and passes out through a pipe2l into the cylinder chamber 23 to cause the piston I6 and table II to move toward the right (Figs. 1 and 2). During this movement of the table I I, fluid within the cylinder chamber 24 exhausts through the pipe 26 and through a valve chamber 285 located between the valve pistons I82 and I83 and passes out through an exhaust pipe 206.

Start and stop valve A start and stop valve 2 I0 is provided for controlling the exhaust of fluid from the reversing valve 26. A manually operable actuating knob 299 is mounted on the outer end of a valve stem 2II by means of which the valve 2H3 may be manually controlled. This valve 2! is a piston type valve comprising the valve stem 2 having formed integrally therewith valve pistons 2I2, 2I3, 2M, 2I5, 256 and 2I1. In the position of the valve 2 I 9 (Fig. 2), a by-pass is provided .to facilitate a manual traversing movement of the table II. A pipe 2I8 and pipe 2I connect the valve chamber 294 in the valve 28 with a valve chamber 2I9 formed in the start and stop valve 2H1. A similar pipe 228 connects the chamber 285 of the reversing valve 28 with the chamber 2I9 of the start and stop valve 2I6. It will be readily apparent from the foregoing disclosure that when the table H is traversed manually by rotation of the traverse hand Wheel I4, fluid may readily by-pass from the cylinder chamber 2-3 through the reversing valve 28, through the by-pass valve chamber 2I9 in the start and stop Valve 2 II], and into the cylinder chamber 24, .thus allowing free manual traverse of the table I I without the necesfluid exhausting through the pipe 205 from the reversing valve 253 will pass through the V-port 221 and out through a pipe 22-2. The pipe 222-is connected to exhaust fiuidfiinto the reservoir I48.

Coolant supply It is desirable to provide a suitable coolant fluid supply for supplying coolant fluid-or grinding lubricant to the grinding wheel and work at the point of grinding contact therebetween. Ina machine adapted for-automatic operation, it is desirable toprovide a coolant system whereby the cool ant fluid may be automatically started and stopped in timed relation with the. grinding operation. As illustrated in Fig. 2 of the drawings, coolant fluid maybe supplied through a pipe 23u from asuitable source (not shown), such as a coolant tank in or adjacent to thebasc of the machine or from a main coolant supply located at a station remote from the grinding machine. Fluid passing through the pipe-23ll is controlled by a gatetype valve 23!. When the valve-23l is opened, coolant fluid may pass through a pipe 232, through a'manually operable valve 2M, to a coolant spout 242 which is adjustably supported to convey coolant fluid to the grinding wheel 42 and the work piece 21.

The valve 23 i is provided with a valve stem 233-which is preferably actuated automatically by a hydraulically operated mechanism in timed relationship with the other mechanisms of the machine. This hydraulic mechanism may comprisea fluid pressure-cylinder 23lt mounted on the base Ill (Fig. 1) which contains a slidably mounted piston 235. The piston "235 is connected to one end of .apiston rod 236, the other end of which is connected by a stud with the valve stem 233;. A compression spring 23'l serves normally to hold the piston 235 in the-positionillustrated in'Fig. 2'with the'gate valve-231 closed. When his desired to open the'gate valve 231 and" thereby start the flow of coolant flui'd, fluid under pressure is admitted through a :pipe 238 into a cylinder chamber 239 to cause the piston 235to move toward the right, thus moving :the valve stem .1233 toward the right to open the "valve 231 An adjustable stop screw Mois providedto limit:

Table dwell control value It is desirable to provide asuitable dwell control means whereby in a traverse-grinding operation the table may be caused todwell forapredetermined adjustable period at reversal so that; the grinding wheel may be fed into the work while the table and work piece arestationary- A dwell control valve 250is provided which-is arranged to control fluid exhausting through either a, pipe 25! or a pipe 252. Fluid exhausting through either the pipe 25! or the pipe .252

enters a chamber 253 in the valve 250 and may pass out through .a V-port i254 and a pipe .255 which exhausts into the reservoir W8. A manual actuating. knob 255 is mounted on the outer end of the valve stem 250 and is located onthe front chamber 82' exhausts through the passage 93, the

10 of the machine base. By a rotary adjustment of the knob 256, the V-port 254 may be adjusted so that the amount of fluid exhausting from either the pipe or 252 may be readily controlled so'as to produce the desired dwell at the ends of the table stroke.

Vane motor-Feed control It is desirable to provide suitable means for regulating the speed of rotation of the vane 88 of the-varremotor so that the speed thereof may be readily controlled for either a plunge-cut or a traverse grinding operation. When it is desired to start afeeding cycle, the knob I39 is moved toward the left (Fig. 2), which movement serves to admit fluid underpressur-e into the valve chamber 91 to shift the valve stem 98 toward the rightso that fluid under pressure passing through thepipe :lil5willenter the valve chamber 99 and pass through the passage into the motor chamber 9! to cause a counterclockwise movement of the vane 88', thereby producing an infceding :movementof the grinding wheel 42. During this movement, fluid within-the motor valve chamber me, and passes out through a pipe ZJiwhich passes fluid through a chamber in a selector valve 258 (section flab-Fig, 2) and out througha pipe "259 to a needle type throttle valveizlill' whi'ohiis providedwith a manual actuating'kn'ob 261.. This valve-ispreferably arranged so that the actuatinglknob 261: Jisv located on the front of the machine base to facilitate adjustment thereof duringagrinding operation. Fluid passing'through the throttle valve 260 may pass outthrough apipe 262 which exhausts into the til reservoir M8. It will be readily apparent from the foregoing disclosure that by controlling theuaperture'oftlrevalve 26B, thespeed of counterclockwise rotation of the vane 88 may be readily controlledto produce the desired plunge-cut feeding operationof the grinding wheel 42.

If the-machineisset upfor a traverse grindingoperation, a rotor 263 of the selector valve 258 is rotated 45 degrees/in a clockwise direction- (Figs. 2 and 1.10) so that fluid from the vane motor chamber'liz exhausting through the pipe 2%! andtheselector valve 2581) (Fig. 2) passes through apassage 264 in the selector valve rotor 263 and passes out through a pipe 265 and through a needle type throttle valve 266. The needle val ve 265 is provided with a manual actuating knob 26l'1ocated on the front of the ma- 1 chine base to facilitate adjustment of the valve from theroperators controlstation.

Ina traverse grinding operation, it is desirable that ithe grinding wheel be fed into the work only during reversal of the table, that is, at the ends of a grinding stroke. It is, therefore, desirable'to provide control means for .allowing *a predetermined amount of exhaust to pass throughlth'e needle valve 256 during reversal ofthework table movement. The valve 2% is connected by a pipe 268 with a fluid presreservoir I48.

In order to provide an infeeding movement of 11 the wheel slide 38 durin reversal of the table i l, a suitable control valve H3 is provided. This valve is preferably a piston type valve comprising a valve stem 214, the right-hand end of which is connected by a stud 2'15 which is supported on the uppe end of the rock arm I90. It will be readily apparent from the foregoing disclosure that each time the reversing lever 192 is actuated to cause a reversal in direction of movement of the Work table II, the rock arm l90 will actuate the valve stem 2M. Fluid under pressure from the pump passing through the pipe 252 enters a chamber formed adjacent to the right-hand end of the valve 20 and is arranged to pass through a passage 21! into a valve chamber 2118 formed in the valve stem 214. In the position of the valve "N3 (Fig. 2), fluid entering the chamber 2'83 passes out through a pipe 219 and through a needle type throttle valve 283 into a chamber 28! formed at one end ofv the shuttle type valve 269 to cause the piston 2'!!! to move into its uppermost position (Fig. 2). During this movement of the piston 2'50, fluid within a similar chamber 28! may exhaust through a needle type throttle valve 283 and a pipe 234 into a chamber 285 formed in the valve stem 274 and pass outwardly through a pipe 286 which returns exhausting fluid to the reservoir M8. Similarly, when the reversing valve 29 is shifted at the other end of the table stroke, the valve stem 214 is shifted toward the right (Fig. 2) so that fluid under pressure passes from the valve chamber 278 through the pipe 2851 into the fluid chamber in the valve 269 to cause a reverse movement of the piston 270. By adjustment of the throttle valves 280 and 283, the speed of movement of the valve piston 210 may be readily controlled so that a desired amount of fluid exhausting through the pipe 268 may pass through the valve chamber of the valve piston 210 and out through the pipe 212 into the eservoir 848 so that the vane 88 may rotate through a predetermined arcuate distance during each reversal of the table I l to impart a predetermined infeeding movement to the grinding wheel 42 at each end of the table stroke.

In an automatic plunge-cut grinding operation, it is desirable to provide a suitable mechanism so that the valve Ell may be manually shifted to initiate a grinding cycle, after which the valve 66 may again be automatically shifted to terminate the grinding operation after the work piece 2'! has been ground to a predetermined size. In order to provide free movement of the feed control valve 66 so that it ma be readily shifted without bucking fluid under pressure, a fluid operated four-way valve 296 is provided. The valve 293 may be a standard valve, such as that manufactured by Vickers, Inc. As shown in Fig. 2, fluid within an end chamber 29l of the valve 551 may exhaust through a pipe 292, through a valve chamber 293 in the valve 290, and pass outwardly through an exhaust pipe 294 which returns exhausting fluid to the reservoir I48. It will be readily apparent that in the position illustrated in Fig. 2, the valve 60 may be readily moved toward the left without undue effort on the part of the operator, so as to initiate a plunge-cut grinding feed.

A suitable cycle time control valve 380 is provided for controlling the duration of the grinding cycle. This valve is a piston type valve comprising a slidably mounted piston 30 I. When the feed valve 60 is moved toward the left into a grinding position, fluid unde pressure'passing 12 from thevalve 60 through the pipe 6| passes through a chamber 362 formed in the rotor 263 of the selector valve 258 (Fig. 2) on section line CC (Fig. 9) and passes out through a pipe 303 into a valve chamber 394 to cause the piston 30! of the timer valve 390 to move toward the left (Fig. 2). During this movement of the piston 30!, fluid exhausts from a chamber 365, out.

through a pipe 326, through a needle type throttle valve 3G1, through the pipe 64, into the valve chamber Hi5, into the valve 60 and passes out through the exhaust pipe it! into the reservoir Hit. It will be readily apparent from the foregoing disclosure that by regulation of the throttle valve 391, the speed of movement of the piston 39! may be readily controlled as desired. After the valve piston Sill has moved to a predetermined position in its movement toward the left, fluid under pressure within the valve chamber 384 may enter an internal circular groove and pass through a pipe 308 which conveys fluid into an end chamber 309 in the valve 290 to shift the valve stem toward the left so that fluid under pressure from the pump Z30 passing through the pipe H4 may pass into the valve chamber 293 and through the pipe 292 into the valve chamber 29! in the valve 60 to shift the valve stem I35 toward the right into the position illustrated in Fig. 2. This movement of the valve 60 serves to reverse the flow of fluid to the wheel slide cylinder 57 and also to the vane motor so that the grinding wheel slide 38 and the grinding Wheel 42 are moved automatically to a rearward or inoperative position.

The movement of the timer valve piston 30! toward the right is limited by a manually adjustable stop screw 3H which is actuated by means of a manual control knob 3|2. When fluid under pressure is passed through the pipe 64 to re-set the timer valve 300 and also to return the wheel slide 38 to its rearward position, fluid may pass through the needle valve 301 into the timer valve chamber 305 and may also pass freely through a check valve 3l3 into the chamber 305 so that the timer valve piston 30! may be returned rapidly to its right-hand or initial position (Fig. 2) Sim-- ilarly, fluid exhausting through the pipe 308, after the piston 38! covers the port at the end of the pipe 308, may pass around an internal groove formed in the casing of the valve 300 and out through a check valve 3 I 4.

In order that the work rotation may be automatically started and the coolant fluid automatically turned on in timed relation with the plungecut infeeding operation, fluid under pressure passing through the pipe 6! to the selector valve 2580 may pass through a valve chamber 3H] formed in the rotor 263 and may pass out through the pipe I15 to convey fluid under pressure to the cylinders I69 and 234, as above described, automatically to start the work rotation and to turn on the supply of coolant fluid.

It is desirable to provide a suitable control mechanism which is operative on both a plungecut feed and also a traverse grinding feed so that the vane 88 of vane motor 85 moves initially at a comparatively rapid rate to take up the backlash between the feed screw 50 and the half nut 5|. This mechanism serves to take up the backlash in the feed mechanism before the grinding wheel engages the work to be ground. When the grinding wheel moves into grinding engagement with the work piece lever the speed of movement on the vane 88 is reduced to a predetermined grinding feed as governed by the needle valve 260 on a plungeacut grinding 'o'peration or by the rieedle valve 266 during a traverse grinding operation. This control mechanism mayalso-be utilized if desired to produce a shouldergrind-ing feed at a comparatively rapid rate for grinding a shoulder on the Work piece a'fterwhich it may Ice-slowed down to a normalbody orgrinding feed as gover-n'e'd' by the throttle valve zfill.

I his mechanishr may comprise a shuttle type valve 3 lEhaving a-slidably mounted valve piston 336. The valve piston 3I6 is-provided with a valve chamber which is arranged so th'at' "fluid may pass from the' pipe 251, through the valve chamber in'to a pipe 3H during the movementf the'valve piston 3lfi in either direction. The amount of fluid passing through the pipe 3I1 may be 'rea'dily controlledbymeans ofan adjustable n'ee'dle'va-lve 349 so that the exhaust'ofii passing" through the shuttle valve 315 may be readily controlled. Fluid e'xhaust'ingthroughthe needle valve 3I9 may pass through a pipe 320 which returns exhausting fluid to the reservoir I48. A needle valved-2'1 is provide'd'in the pipe line -'I*-Il3"to throttle fluid exhausting from a valve chamber 322 formed at the lower end ofthe shuttle valve 3 l 5so' as tocon trol'the rate of down- Ward movement of the shuttle valve piston '3 It: A check valve 323 is connected in the pipe line I03 so that when fluid under pressureispass'ed through the pipe I03; it m'ay pass rapidly through the check valve 323 mm the shuttle valve chamher 322 to cause a rapid upward movement of the shuttle valve piston 3 E. When'fiuidunder pressure is passed through "the pipe IM into a valve chamber formed at the upper end of the shuttle valve 3I5to cause adow nwardmovement of the piston Sid-fluid ma beexhaustedfrom the lower chamber-3Z2 at a readil controlled rate by manipulation: of the needle'valve" 32 l -so that a controlled amount of exhaust fluid may be passed from thepipe 251 into the pipe -3I8. This exhaust of fluid through the pipes 251 and 3H is in addition to the exhaust permitted by the setting of the needle valve 250 so that during the passage of the valve chamber of the shuttle piston 3 l6 by the pipe 251 an increasedspeedmay be obtained in the rotation of the vane 88 of the motor 85 to provide-the desired shoulder grinding feed. After the valve'ohamber passes by the end of the pipe 251, the entire exhaust of fluid fro'm'the vane motor chamber 92 must pass through the needle valve 2'60 which is set to provide the desired body grinding feed for grinding a cylindrical portion of the'work piece. The shuttle valve 3| 5, in addition to-serving as a means for providing a shoulder grindingfeedwhe'n desired, also serves to cause a-slightly'rapid movement of the vane 88 which serves during the initial stages of the plungecut -grinding cycle, in case no shoulder grinding feed is required, to take up the backlashlbetween the feed screw 50 and the half nut 5|.

By adjustment of the needle va1ve'32I, the length of duration of the shoulder grinding feed may be readily regulated. By adjustment of the needle-valve 319, the rate of theshoulder grinding ieed may be readily adjusted as desired.

I The selector valve 25B is shown in sectional view in -Fig; 9, including the valve rotor 263 which is formed integral with a valve stem 330. A manual actuating knob 331 is fixedly mounted on the outer end of the valve stem 330 by means of which the valve rotor 263 may be readily adjusted. To facilitate positioning the selector valve 258, the valve stem 33!) is provided with a pin- 332 which projects inthe pathof a =stud 333--carried by the casing or the 'valve s and a stud-33d which is also fix edl'y mounted on thevalve casing (Fig. l0).' When the pin '332 is in the full line position as indicated in Fig. '10, the selec'tor valve 258 isset fora plunge cut grinding cycle, in which theg'rindin'g wheel-42 is fed directly into the Work fora continuous'stroke while the workpiece 21 is rotated-*an'd held against axial movement. If it is desired'toshift from a plunge-cut feed to a traverse grinding feed, the knob 33I and the valve stem 330 may be rotated in a clockwise direction so that thepin- 332 is in position 332a (Figs. 2 and 10) in enga'gement with the stop pin 334 which shifts the valve rotor 45 in-a clockwise direction irorn t'he sectional positions illustrated diagramrnatioa-lly in'Fig. 2. It will thus be readily appareritthat by nianipulation of the selector valve knob 33 b, the machine maybe readily shifted from a plunge cut grinding operation to a traverse grinding operation where an infeeding of the grinding wheel 42 is obtained only at the ends of thewor k table stroke.

To set the machine up for a traverse grinding operation, the valve rotor 2 83 is rotated in a clockwise direction so that the pipe I03' connects by means of a rotor chamber with a pipe 340 toco'n vey fluid to and exhaust fluid from the start and stop valve ilill. Inthis position of the valve rotor of'the selector valve 258a, the pipe BI is disconnected from thepi-pe I04 and the pipe I04 is connectedwiththe pipe I63 Which-'is-in turn connected with the start-and stop valve ZIIL When it is desired to start a traverse grinding operation, the knob 2fl9is pulled out, thatis, toward the left (Fig. 2), and fluid is allowed to exhaust from the valve chamber IUI of the control valve 95 and also from the valve chamber 322 of the shuttle yeti/e315. Simultaneously, the valve pi tohs fl l-iandW6 0i the valvestem- 2'II allow'fluid under pressure to flow through the pipe I63 into a chamber in valve rotor 263 of the selector valve ziiild and into th'epipe IB'4 which is connected'to the control valve 95; Fluid-enters the valve chamher 9? and shifts the valve stem 96 toward the right (Fig. 2) to *facilitate feeding of the grinding wheel-" 12. No movement of the vane 88 is obtaineduntil the shuttle valve 315 is also connected to the pipe I04. The fluid from the pipe I04 shifts the shuttle piston 3I6 and allows apredetermined amount of fluid to exhaust from the moto'r chamber 92 and thus move the vane as and thereby feed thegrinding wheel 42 towardth'e worker only take up backlash as desired. In this posit-ion oi the selector valverotor 2E3 2 581)), the

pipe H5 so that the actuation of the positions-I10 and 7535 is controlled by the valve stem 211 of the start and stop valve 2 H).

The cp'eration of this improved grinding machine will bereadily' apparent from the forego ingidiscl'o'su-re. Assumingall of 'the'valves to havebeen-previously adjusted 'and set, when it is de sired-to start a grinding operation, the headstockswitch [So is-closed to render the-headstock electrical circuit operative, the grinding wheel driving motor 43 is started, and the fiuidlpump 280 is also started. As shown in Fig. 2, the valves are set for a plunge-cut grinding operation, a work piece 2'! is placed in position on the work centers 28 and 29 and the table H is traversed longitudinally to position the desired portion of the Work piece 21 in operative position opposite the grinding wheel 42. The lever I21 is then rocked in a clockwise direction (Fig, 1) to throw the feed gear H3 into position ll3a in mesh with the gear l3 (Fig. 3). The knob 33l of the selector valve 258 is then positioned as shown in Figs. 9 and 10 to position the valve parts as shown in Fig. 2 in positions 258a, 2581) and 2580 so as to render the cycle time control valve 308 operative to control the duration of a plunge-cut grinding cycle. The knob N9 of the feed control valve 68 is then pulled out, that is, toward the left (Fig. 2) to initiate a plunge-cut grinding cycle. The shifting of the feed control valve 68 serves to start the rapid approach of the grinding wheel 42 and H through the selector valve 2-58 starts the headstock driving motor 32, to open the valve 23l so as to start the flow of coolant fluid, and allow controlled exhaust of fluid from the vane motor 85 to produce the desired plunge-cut infeeding cycle.

The vane 88 of the vane motor 85 moves first at a comparatively rapid rate as controlled by the shuttle valve 3 I to take up the backlash between the feed screw 58 and the half nut 5| before the grinding wheel 42 engage the work piece 21 to be ground. The movement of the vane 88 then slows down to a predetermined grinding feed as governed by the throttle or needle valve 268.

The plunge-cut feed continues for a predetermined time interval as controlled by the cycle timing valve 388. After the predetermined time interval, fluid is admitted to the chamber 29! of the feed control valve 68 to shift it toward the right into the position shown in Fig. 2 so that fluid under pressure will be admitted to the cylinder chamber 63 rapidly to move the grinding wheel 42 and its supporting slide 38 to a rearward or inoperative position.

If it is desired to set up the machine for a traverse grinding operation, the lever I2"! is similarly thrown in a clockwise direction to engage the tumbler feed gear l !3 with the gear 13. The knob 33l of the selector valve is rotated in a clockwise direction (Fig. through approximately 45 to re-position the valve rotor 263 for a traverse grinding operation. This re-positioning of the selector valves 258 serves to render the vane type feed motor 85 operative to impart an intermittent infeeding movement of the grinding wheel 42 at the ends of the work table stroke. The knob 209 of the start and stop valve 2 I8 is then pulled out, that is, toward the left (Fig. 2) which allows fluid under pressure to exhaust from one of the chambers of the table driving cylinder l5 to start a reciprocating movement of the table for a traverse grinding operation. Shifting of the start and stop valve 2m to this position also serves through the selector valve 258 to start the headstock motor 32 and to open the valve 23I to turn on the coolant fluid.

Through the selector valve 258, fluid is admitted to the valve chamber 91 to shift the valve stem toward the right, so that fluid under pressure is admitted to the motor chamber 9| to rapidly move the vane 88 in a counterclockwise direction rapidly to take up the backlash between the feed screw 50 and the half nut 5|. The initial rapid movement of the vane 88 is governed by the shuttle valve 3H3 and the needle valve 32L After this initial movement, the vane 88 is moved intermittently, during the reversal of the table at each end of its stroke, as governed by the shuttle valve 269 and the throttle valve 266.

The infeeding movement of the grinding wheel 42 at the ends of the table stroke is controlled in a manner above described by allowing a predetermined amount of fluid to exhaust from the vane motor during each reversal of the movement of the table I I; It will thus be seen that by adjustment of the control valves, either a plunge-cut grinding operation or a traverse grinding operation may be readily obtained as desired.

After either a plunge cut or a traverse grinding operation has been completed, fluid under pressure is admitted to the cylinder chamber 63 to move the grinding wheel rearwardly to an inoperative position and is also admitted to the motor chamber 92 to return the motor vane 88 in a clockwise direction to its initial position.

It will thus be seen that there has been provided by this invention apparatus in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. A grinding machine having a base, a longitudinally reciprocable work supporting table, a rotatable grinding wheel, a transversely movable slide therefor, means including a piston and cylinder to move said grinding wheel rapidly to and from a grinding position, means including a fluid motor to produce a grinding feed, control means for said fluid motor to produce a continuous plunge-cut grinding feed of said wheel, control means for said fluid motor to produce an intermittent infeed of the grinding wheel during table reversal for a traverse grinding feed, and a selector valve whereby either of said control means may be rendered operative while the other remains inoperative.

2. A grinding machine having a base, a longitudinally reciprocable work supporting table, a rotatable grinding wheel, a transversely movable slide therefor, means including a nut and screw mechanism to feed said slide, means including a piston and cylinder to move said feed screw axially to impart a rapid movement of the grinding wheel to and from a grinding position, means including a single vane-type fluid motor to rotate said screw to impart a relatively slow grinding feed to said slide, control means for said fluid motor to produce a continuous rotary movement of said vane to impart a continuous plunge-cut feeding movement of said wheel, control means for said fluid motor to produce an intermittent rotary movement of said vane to impart an intermittent infeeding movement of the grinding wheel during each table reversal for a traverse grinding operation, and a selector valve whereby said fluid motor vane may be actuated either continuously for a plunge-cut or intermittently for a traverse grinding operation.

3. In a grinding machine having a base, longitudinally reciprocable work supporting table, a rotatable grinding wheel, a transversely movable slide therefor, means including a piston and cylinder to reciprocate said table, a table actuated reversing valve for said cylinder, means includl7- ing a nut and screw to feed said slide transversely, means including a fluid motor to rotate said screw so as to impart a feeding movement to said grinding wheel, a control valve for said motor, a needle valve to control the movement of said motor in one direction, a fluid actuated shuttle valve to control the exhaust of fluid through said needle valve, and means actuated by andin timed relation with said table reversing valve to actuate said shuttle valve during table reversal thereby to facilitate metering a predetermined volume of fluid through said needle valve to actuate the fluid motor and therebyimpart a feeding movement to said grinding wheel.

4. In a grinding machine in accordance with claim 3, the combination with the parts and features therein specified, of a throttle valve to control the rate of movement of said shuttle valve so as to regulate the extent of said feeding movement at each reversal of said table.

5. A grinding machine having a base, longitudinally reciprocable work supporting table, a rotatable grinding wheel, a transversely movable slide therefor, means including a fluid motor to feed said slide to impart a grinding feed to said wheel, a manually operable control valve to initiate a grinding cycle, control means including a throttle valve to control the exhaust of fluid from one side of said fluid motor so as to control the rate of movement of said motor and thereby control the rate of the feeding movement of the grinding wheel, a fluid actuated shuttle valve arranged to allow a predetermined exhaust of fluid from said motor during the initial feeding movement to facilitate an initial rapid movementof the wheel slide to take up backlash between the parts of said feeding mechanism, a needle valve to control fluid exhausting from said shuttle valve to regulate the rate of said rapid movement of the slide, and a throttle valve to regulate the rate of movement of the shuttle valve so as to regulate the length of said initial rapid movement of the wheel slide.

6. A grinding machine having a base, a longitudinally reciprocable work supporting table, a rotatable grinding wheel, a transversely movable slide therefor, means including a nut and screw to move said slide transversely, means including a fluid motor to rotate said screw to impart a grinding feed to said wheel, a manually operable cycle control valve to initiate a grinding cycle, control means including a throttle valve to control the exhaust of fluid from one side of said motor so as to control the rate of rotation of said motor and said screw so as to control the rate of feeding movement of the grinding wheel, a fluid actuated shuttle valve arranged to allow a predetermined exhaust of fluid from said motor during the initial feeding movement to facilitate an initial rapid rotation of the feed screw to take up the backlash between the nut and screw before the grinding wheel engages a work piece, a needle valve to control fluid exhausting through said shuttle valve to regulate the rate of said rapid rotation of the feed screw, and a throttle valve to regulate the rate of movement of said shuttle valve so as to regulate the length of said initial rapid rotation of the feed screw.

7. A grinding machine having a base, a longitudinally reciprocable work supporting table, a rotatable grinding wheel, a transversely movable slide therefor, means including a nut and screw to move said slide transversely, means including a fluid motor to rotate said screw to impart a grinding feed to said wheel, a manually operable control valve to initiate a grinding cycle, control means including a throttle valve to control the exhaust of fluid from one side of said fluid motor so as to control the rate of rotation of said motor and said screw to control the rate of the feeding movement of the grinding wheel, a fluid actuated shuttle valve arranged to allow a predetermined exhaust of fluid from said motor during the initial feeding movement to facilitate an initial rapid rotation of the feed screw to take up backlash between the nut and screw, a needle valve to control fluid exhausting through said shuttle valve so as to regulate the rate of said rapid rotation of the feed screw, a throttle valve to regulate the rate of movement of the shuttle valve so as to regulate the length of said initial rapid rotation of the feed screw, and means automatically to shift said control valve to a reverse position after a predetermined grinding operation to return said fluid motor to its initial position and also to return the grinding wheel to its initial or inoperative position.

8 A grinding machine having a base, a longi tudinally reciprocable work sup-porting table, a

wheel. means including a fluid motor to rotate said screw to impart a grinding feed to said wheel, a manually operable control valve to admit fluid under pressure to said cylinder and said motor to initiate a grindingcycle, control means include ing a throttle valve to control the exhaust of fluid from one side of said motor so as to control the rate of movement of said motor and rotation of said screw so as to control the rate of feeding movement of the grinding wheel, a fluid actuated shuttle valve arranged to allow a predetermined exhaust of fluid from said motor during the initial feeding movement to facilitate a rapid rotation of the feed screw to take up backlash between the nut and screw, a needle valve to control fluid exhausting through said shuttle valve to regulate the rate of said rapid rotation of the feed screw, a throttle valve to regulate the rate of movement of said shuttle valve so as to regulate the duration of said initial rapid rotation of the feed screw, and means automatically to shift said control valve to a reverse position after a predetermined grinding operation to return said piston and said fluid motor to their initial positions and thereby move the grinding wheel and its supporting slide to an inoperative position.

9. A grinding machine having a base, a longitudinally reciprocable work supporting table, a rotatable grinding wheel, a transversely movable slide therefor, means including a nut and screw to move said slide transversely, means including a piston and cylinder to move screw axially rapidly to position said slide and grinding wheel, means including a fluid motor to rotate said feed screw to impart a grinding feed to said wheel. control means therefor including a throttle valve to control the exhaust of fluid from one side of said motor so as to control the rate of said motor and the rotation of said screw to control the rate of feeding movement of the grinding wheel. a fluid actuated shuttle valve arranged to allow a predetermined exhaust of fluid from said motor during the initial feeding movement to facilitate a relatively rapid shoulder grinding feed, a needle valve to control fluid exhausting through said shuttle valve to regulate the rate of the shoulder grinding feed, and a throttle valve to regulate the rate of movement of said shuttle valve so as to regulate the length of said shoulder grinding feed. I

10. A grinding machine having a longitudinally reciprocable work supporting table, a rotatable grinding wheel, a transversely movable slide therefor, a nut and screw to feed said slide transversely, means including a piston and cylinder to impart a rapid axial movement to said feed screw to position the grinding Wheel either in an operative or inoperative position, means including a fluid motor to impart a slow rotary movement to said feed screw, means including a manually operable control valve to admit fluid under pressure to said cylinder to move the grinding wheel to an operative position and thereafter to admit fluid under pressure to said fluid motor to initiate a grinding feed, and a time control valve to control the duration of said grinding feed, said time control valve being arranged after a predetermined movement to admit fluid under pressure automatically to shift said manually operable control valve and thereby ter minate the grinding operation by reversing the flow of fluid under pressure to said cylinder and to said motor.

11. A grinding machine having a base, a longitudinally reciprocable Work supporting table, a rotatable grinding wheel, a transversely movable slide therefor, a hydraulic feed motor which is arranged to feed said slide, means including control valves for said motor to impart either a continuous uniform feed to said slide for a plunge- 20 cut grinding operation or an intermittent feed to said slide at the ends of the table stroke 'for a traverse grinding-operation, an electric motor to rotate a work drive motor, means including a switch to start the work drive motor, means ineluding a piston and cylinder to actuate said switch to start said work drive motor, means including a source-ofcoolant fluid, a control valve therefor, means including a piston and cylinder to open said coolant supply control valve, and a selector valve which is arranged in either a tray-- erse grinding or a plunger-cut grinding position to start the Work drive motor and turn on the coolant fluid when the grinding operation is started,

HERBERT A. STLVEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,048,453 Holt Dec. 24, 1912 1,806,664 Belden et al. May 26, 1931 1,816,750 Steiner et a1 July 28, 1931 1,911,553 Cole et al May 30, 1933 1,961,849 Fraser June 5, 1934 2,163,246 Maglott June 20, 1939 2,205,373 Decker June 18, 194.0 2,254,002 Decker et al. Aug. 26,. 1941 2,294,872 Wood Sept. 1, 1942 2,335,356 Price et al Nov. 30, 1 943 7 2,376,236 Decker et al May 15, L945 

